Darrell Markewitz is a professional blacksmith who specializes in the Viking Age. He designed the living History program for L'Anse aux Meadows NHSC (Parks Canada) and worked on a number of major international exhibits. A recent passion is experimental iron smelting.
'Hammered Out Bits' focuses primarily on IRON and the VIKING AGE

Friday, March 27, 2015

Darrell Markewitz will investigate air supply into a Viking Age furnace.

I had not realized how cut up the original description had gotten - and this was the point of a bulk mailing that had been sent out earlier this week

This is from the longer text version:

Darrell's first attempt at a bloomery furnace was at a research
session for Parks Canada in an attempt to re-create the first iron smelt
in North America by the Norse (about 1000 AD). Since then, he has
concentrated on re-discovering lost Northern European techniques from
the Late Iron Age, using the process of experimental archaeology.
Darrell was a team leader for all of the previous Early Iron symposiums,
as well as another core member of the Smeltfest research workshops. He
has taught historical iron smelting both in Canada and the USA, as well
as taking part in research projects in Denmark and Scotland.
www.warehamforge.ca/ironsmelting

Darrell will be undertaking an experimental archaeology project which
also will provide a more basic level furnace construction and operation
sequence for less experienced bloomery iron makers. The furnace will be a
'Norse short shaft' type, to be built over the early afternoon on
Friday. The smelt on Saturday will employ a 'bog ore analog' and the
experiment will centre on using multiple double chamber bellows linked
to a bladder as a possible method to produce high air volumes. Participants actively sought!
Friday afternoon - build
All day Saturday - smelt

The core here is my ongoing research into possible VA iron smelting
techniques. Archaeology actually only gives us broken remains of only
the last step in a complex multi-step process, and usually heavily
eroded at that. Modern re-constructions using various variations on
Norse type twin chamber bellows most commonly produce smaller, lacy
blooms. The few artifact blooms surviving are larger and more dense,
more like the blooms made using much higher air volumes.
My question is 'how do you get high air volume from small capacity
bellows?' One at least theoretical possibility is linking a number of
smaller 'blacksmith's' bellows via a leather bladder (animal skin).
Placing a board and weight on top could serve to modify delivered air
pressure (another important factor effecting smelting furnace dynamics).
This system may also suggest something about the social dynamic around
small scale iron production in the Viking Age.

I do hope some of the readers in the NE region of the USA might consider Early Iron 4.

Sunday, March 22, 2015

Even after
almost two decades of many trials and frequent failures, many puzzles of
exactly how historic direct process bloomery furnaces work still
remain.Early Iron 4 will once again pull together those who continue to
experiment. Lee Sauder, certainly the most experienced and best
known worker with direct process bloomery furnaces in North America,
will build and fire an experimental furnace based on the medieval
Spanish Catalan type, assisted by 'Early Iron' instigator Mike McCarthy.Jesus
Hernandez, one of the top bladesmiths making and using bloomery iron in
the USA, will bring his understanding of the Catalan as well as share
his extensive experience with 'bloom to blade'. Darrell Markewitz
will investigate air supply into a Viking Age furnace. Early Iron 4 will
not just allow participants to observe, participate and learn. It
represents a chance to pull together individuals interested in all
aspects of the riddle of Early Iron, face to face - to the enrichment of
us all.

We are excited to be sharing the
Ashokan Campus with the Northeast Blacksmiths Association for their
Spring Hammer-In. Learn more about their program at Northeast Blacksmiths Association

Mike McCarthy guides a working team

Lee Sauder adding charcoal at Early Iron 2.

Nami ni Chidori Nagamaki by Jesus Hernandez

Historic illustration of the Catalan furnace

New
to iron smelting and blacksmithing or just curious? A special area and
time will be reserved for hands-on practice of fire-tending and basic
forging skills. Tools, equipment, and coal are provided and available
for purchase on site. Student discounts and parent/child scholarships
are available. For more information, go to the Early Iron website.

Saturday, March 21, 2015

I was wondering if you could help me with a bellows related
question, namely proportions. The style I'm trying to make are seen in
medieval artwork, side by side connected by a lever and rope. I know how
long I need them to fit my setup (36" overall) but the width and height
when inflated is the main issue.

I have never made that particular style. I have seen a number of medieval depictions.
On a guess from the rough period of the historical illustrations, these
are most like (??) to date to time when charcoal was still the primary
fuel.

Typical of many Medieval illustrations, you can see the artist did not draw a working system!

The exact mechanics of how these work is hazy. The illustrations (sometimes) show a
bar or rope off one side of the cross bar linking the pair of individual
chambers. To get this to work there would also have to be a counter
weight on each of the bellows top plates.

Pull down on the handle lifts
the opposite chamber to fill it, on the near chamber the weight on the top plate is
forcing it closed and exhausting.

Letting go the handle reverses the
blast / fill process. I would think that the weights might have to be
considerable to get this all to work effectively. The weight on the far chamber would have to not only close that one, but also be enough to provide the lift for the near chamber. Arm power would be
every second 'blast', and the pressure of the blast would be fixed only by
the weight size. It seems to me it might be hard to get an even constant blast between the two chambers (??) Maybe if the power was supplied by a solid stick, you could be providing arm power on the exhaust for both sides (???)

The Viking Age 'double chamber' side also alternates side to side as the
later type you are describing. I have worked these, and have made a
number of reconstructions based on the evidence available (quite limited
mind you!) The rough size of each chamber is 60 cm long x 30 cm at the
widest. Normal loft height is about 30 - 35 cm. The maximum volume there is roughly 120 LpM. ( If you run a search on 'blacksmith bellows' here you will find a number of earlier postings dealing with these. )
This bellows system will effectively create a 'ball of heat' in hardwood charcoal
roughly 4 - 5 inches in diameter. Welding heats certainly possible. (The
bigger problem is how fast the fuel is consumed, dropping unlit 'cold'
charcoal into the heat zone.) Remember that Saxon and Viking Age pattern
welded swords were all made with some variation on this basic
equipment!

This all suggests to me that the needed volume of the later 'twin with
bar' bellows may more be linked to fuel type and the required heat zone (as
determined by work type undertaken). If you are expecting to forge weld large
axes, you certainly need a larger heat zone available than if you are
making simple hooks.
On size, there seems to be a lot of variation on both illustrations and working replicas of early bellows types I have seen.
Roughly, you see a length to width ratio on the individual plates of 2:1
or 3:1 as pretty common. There is also an ideal ratio of inlet to
outlet diameters, 4:1 appearing to be an ideal. I expect this may be
where the real tinkering may lie in an effective design.

My rough guess is that the later period 'great bellows', with two
interlocked chambers stacked on each other, was introduced with the
switch to rock coal in blacksmithing around 1300 +. This just an
estimation, you would have to do further research on that. The advantage
of a great bellows is that there is a larger reservoir of air to
produce a longer, constant blast. At the same time, a fast snap of the
wrist can force a sharp blast of air if desired. You would end up
lifting less counterweight on each arm stroke than with the 'twin with bar'. If any readers have actually built and operated the 'twin with bar' system, I'm certain we all would like to hear of their experiences!

Friday, March 20, 2015

I see that barrel hoops are fairly flexible, but the iron from
the bloom that *I* have ... seems to be fairly rigid even in
the very thin bits. Is this a steel-vs-bloom-vs-cast-iron thing, or is
there a trick to making bloomery iron flex?

Remember that you may certainly be looking at objects made of Bessemer
mild steel (possible for anything after 1855) in those 'antique' barrel
hoops. Most likely you would be seeing something pretty much like (or actually) a
modern mild steel.

Individual iron blooms can vary considerably in actual carbon content, thus potential hardness / rigidity.
Ore type and particle size, layout of the furnace, operating
temperature, size of charges - all can effect the potential results.
If we worked with that granular hematite for your smelting course, that stuff tends to the mid carbon ranges for example.
Even a single bloom usually varies across its diameter, typically the
top surface having a higher carbon than the base. This difference will
often get 'folded in' as the consolidation welding series is undertaken.
(And the welding process itself can change the available carbon
content.)

Proportion of other trace elements in the ore can also effect the
effective hardness / rigidity. Phosphorus for example can certainly make
the metal more brittle. This more a problem with natural bog iron ores,
some of the rock based types. (One of the advantages of the analog we
use here is that we have better control of the elemental content.)

Many contemporary Blacksmiths had pondered the question of just how our metal was made. Almost two decades ago, a few had turned that interest into the first attempts to build ancient and historic iron smelting furnaces, working from hints in often broken traditions and fragmentary archaeological remains. In 2004, Mike McCarthy boldly hosted the first Early Iron Symposium, gathering together people who had previously been working only in isolation. This first event was centered on demonstrations of experimental furnaces based on differing historic systems inspired by European, African and Japanese traditions, by Lee Sauder & Skip Williams, Darrell Markewitz and Mike McCarthy. Following the success of EI 1 came two more annual events, more centered on teaching effective method than pure experimentation. The result of much trial and many errors had lead to the development of simple but more predictable working methods. Those who had kindled that spark then would see it flame and grow. Over the last decade since the last Early Iron in 2005, there has been an explosion of interest in bloomery iron as a material, especially within the Bladesmithing community. It might to be fair to say there is a 'new generation' of talented metalsmiths exploring the possibilities of bloomery iron. There still remains, however, many questions to answer, technical problems to solve, and mysteries to uncover.

Mike McCarthy guides a working team - Early Iron 2, 2005

Early Iron 4 will be turning back to some of those experiments, highlighting the continuing efforts to figure out 'just how it might have been done'. Lee Sauder, certainly the oldest and best known worker with direct process bloomery furnaces in North America, will build and fire an experimental furnace based on the medieval Spanish Catalan type, assisted by 'Early Iron' instigator Mike McCarthy. Jesus Hernandez, one of the top bladesmiths making and using bloomery iron in the USA, will bring his understanding of the Catalan as well as share his extensive experience with 'bloom to blade'. Darrell Markewitz will continue his long investigations into Viking Age ironmaking technologies.

Historic illustration of the Catalan Furnace

Early Iron 4 will not just allow participants to observe, participate and learn. Perhaps most importantly, it represents a chance to gather individuals from all aspects of the riddle of Early Iron, face to face. So many of us work alone, often with little ability for advice on common problems or to share our excited discoveries.

It remains our hope that Early Iron 4 will pull together the researcher, experimenter and practical worker - to the enrichment of us all.

LEE SAUDER :If there was a single person who could be said to have initiated the current 'Early Iron' movement, that person would certainly be Lee Sauder. Assisted by his smelting partner Skip Williams, Lee undertook his first experimental bloomery iron smelts in 1998. Originally inspired by African protoypes, Lee developed a predictable working method through many trials (and often errors!). His patient and open sharing of all this hard won experience has informed and inspired the current generation of bloomery iron makers. As well as hosting the series of Smeltfest research events at his own 'Germinal Ironworks' (Lexington, Virginia), Lee has demonstrated at major events internationally throughout North America, in Europe, and in Africa.

Lee will lead a team through two experimental attempts at smelting in the "Catalan" style furnace. The furnace features a square hearth, with a divided charge of charcoal and fine ore on the tuyere side, and large ore chunks on the other. This (loosely Medieval) Spanish technology has not been examined by modern practitioners as thoroughly a shaft furnaces, so we all expect to learn a few new things, and maybe get some iron too. All day Friday and all day Saturday.

Lee will also give an informal presentation on his recent excursion to the Meroe Iron Smelting Festival in Sudan. This was Lee's second participation in large gatherings of iron makers in Africa. The first was at the the Festival Wed Binde, Burkina Faso in 2008.Friday evening.

JESUS HERNANDEZ :Born in Spain, Jesus did not start to exploit his life long interest in historic blade making until he emmigrated to the USA in the 1990's. His work is strongly rooted in the Japanese traditions, where his attention to fine detail and precision of technique lead him to bloomery iron through experimenting with the Tatara system. Of late his vision has shifted back to his native Spain, both in terms of blade prototypes and research into the Catalan furnace. The quality of his bladesmithing is exceptional, clearly making him one of the primary examples of 'bloom to blade'. Jesus has increasingly been seen as a feature demonstrator, from his home base in Roanoak,Virginia.

Jesus will be forming part of the team (working with Lee) building and operating the experimental Catalan furnace.

Jesus will also deliver a more formal lecture presentation :"From rock to sword: A description of my own experiences reviving King Arthur's myth of pulling the sword from the stone. I will detail my process of managing bloomery iron and steel starting from the smelting furnace and finishing at a polished blade. Strategies in consolidating the bloom and turning it into bar stock. Altering carbon content to a suitable level for ablade. Manipulation of the bars during forge-welding to enhance the appearance of the layers and grain. Tips on forging blades. How to figure out the heat treat for a material with unknown carbon content and/or alloying elements. Finally how to polish the blade to bring out the beautyof the original material."Saturday evening.

MIKE MCCARTHY :Mike's interest in bloomery iron smelting goes back to his work at the Farmer's Museum and his enthusiasm in the philosophy of 'Sole Authourship'. At the start, he had a unique opportunity to attend a workshop with the Japanese 'Living Treasure' Smelt Master in 2003. Mike's original interest was in the early American Adirondack bloomery furnaces. In 2004 he hosted the first Early Iron Symposium, at the Farmer's Museum at Cooperstown NY, followed by another in 2005 and a third at Peter's Valley Craft school in 2006. He has been a core member of the 'Smeltfest' research group since its inception, and has taught any number of hands on workshops and smelting demonstrations. Mike also was the 'other American' at the Festival Wed Binde, Birkino Faso in 2008.

'Inspired by Butler' presentation tomahawk by Michael McCarthy

Mike will be one of your on site hosts for Early Iron 4. Between these duties, he will be assisting Lee with the two Calatan furnace experiments.

DARRELL MARKEWITZ :Darrell's first attempt at a bloomery furnace was at a research session for Parks Canada in an attempt to re-create the first iron smelt in North America by the Norse (about 1000 AD). Since then, he has concentrated on re-discovering lost Northern European techniques from the Late Iron Age, using the process of experimental archaeology. Darrell was a team leader for all of the previous Early Iron symposiums, as well as another core member of the Smeltfest research workshops. He has taught historical iron smelting both in Canada and the USA, as well as taking part in research projects in Denmark and Scotland.

Darrell will be undertaking an experimental archaeology project which also will provide a more basic level furnace construction and operation sequence for less experienced bloomery iron makers. The furnace will be a 'Norse short shaft' type, to be built over the early afternoon on Friday. The smelt on Saturday will employ a 'bog ore analog' and the experiment will centre on using mutliple double chamber bellows linked to a bladder as a possible method to produce high air volumes. Participants actively sought!Friday afternoon - buildAll day Saturday - smelt

GROUP SESSIONS

'Iron in the Hat'A tradition for NBA, their 'Iron in the Hat' both offers a chance for you to pick up some useful / unusual items, and also helps fund the entire event. " Each registrant is asked to bring a donated item or items with a value of $10-$20. It can be tools, materials, crafted items, apparel, books, ...anything that appeals to this kind of crowd. We sell 'one chance' tickets, and run it like a silent auction. "Ongoing, draws Saturday, right after lunch.

Panel Session - 'Experiments and Directions'Join the demonstration team for a general discussion around past and possible future exploration into Early Iron.Sunday Morning

Informal Forging Session Finish off the event with a little forge time. The demonstration team will be on hand for a little hands on trouble shooting. What problems have arisen with your own work with bloomery iron? Hopefully all our combined brain power might help find some answers. Sunday Morning

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Ontario Arts Council

Canada Council

Ontario Arts Council

February - May 2012 : 'Bloom to Bar' Project Grant

February 15 - May 15, 2012 : Supported by a Crafts Projects - Creation and Development Grant

COPYRIGHT NOTICE -
All posted text and images @ Darrell Markewitz. No duplication, in whole
or in part, is permitted without the author's expressed written permission.
For a detailed copyright statement : go HERE